Wireless Local Area Networks (WLANs) are used to provide wireless access to the Internet and/or other communication networks for wireless stations. The IEEE 802.11 standard encompasses a set of Media Access Control (MAC) layer and physical (PHY) layer specifications for implementations of WLANs. The IEEE 802.11 standard defines two modes of operation for WLANs. In the independent mode of operation, the wireless stations can directly connect to each other by setting up an ad hoc network. In the infrastructure mode of operation, communication is provided to the wireless stations through an access point (sometimes referred to as an AP in IEEE 802.11). In the IEEE 802.11 standard, a single AP, together with the wireless stations it serves, constitute a Basic Service Set (BSS). In this regard, the access point is generally responsible for controlling and scheduling all the downlink transmissions in the BSS.
Despite the availability of the two modes of operation, WLANs are massively deployed in the infrastructure mode. In addition, many WLANs comprise more than one access points. While an access point can adjust many MAC layer and PHY layer parameters to improve the performance of the BSS, these adjustments may not necessarily result in improved performances for the whole WLAN when many access points are involved. This is due at least in part to the fact that the radio access mechanism in IEEE 802.11 is based on a random access technique called Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) in which each WLAN network node, either access point or wireless stations, tries to grab the channel independently using a random back-off counter. Therefore, transmissions in the uplink (i.e. from the wireless stations to the access point) and downlink (i.e. from the access point to the wireless stations) in one BSS, and also among multiple BSSs in a WLAN, can collide or interfere with each other. Hence the performances of the BSSs in a WLAN are often correlated as the transmissions in one BSS can impact, or interfere with, the transmissions in a neighboring BSS.
Hence, in addition to distributed network optimization solutions for WLANs, that is solutions where the optimization is performed at the access point level, there are also centralized solutions in which the network optimization is performed at the WLAN level, that is the network is optimized as an entity instead of optimizing each individual BSS in the network. In that sense, radio resource management (RRM) is the process by which the radio resources of the network are controlled and adjusted in order to efficiently use the available resources across the network. Network operators often deploy centralized RRM network controllers, also known as Self-Organized Network (SON) managers, in their networks. These controllers are usually responsible for continuous network performance monitoring and optimization by controlling network level and/or access point level configuration parameters.
Still, while there are various per access point metrics useful to monitor the performance of a given access point, these metrics fail to provide a network-wide view of the performance of the whole network. Without a network-wide view of the performance of the network, it is difficult to ascertain the effects on the performance of the network of modifications to the RRM configuration parameters. Without a network-wide view of the performance of the network, network optimization performed by a network controller may be limited.